This section uses CentOS 6.8 (x86_64) as an example to describe how to configure a user-defined VLAN for BMSs.

The configuration methods of Red Hat, Oracle Linux, EulerOS, and CentOS are similar.

Use a key or password to log in to the BMS as user root.
On the BMS CLI, run the following command to check the NIC information:
ip link

Information similar to the following is displayed.

Among the devices, eth0 and eth1 bear the VPC, and eth3 and eth5 bear the user-defined VLAN.
Run the following command to check whether the /etc/udev/rules.d/ directory contains the 80-persistent-net.rules file:
ll /etc/udev/rules.d/ | grep 80-persistent-net.rules
- If yes, and the file contains all NICs except bond0 and lo obtained in step 2 and their MAC addresses, go to step 6.
- If no, go to step 4.
Run the following command to copy the /etc/udev/rules.d/70-persistent-net.rules file and name the copy as /etc/udev/rules.d/80-persistent-net.rules.
cp -p /etc/udev/rules.d/70-persistent-net.rules /etc/udev/rules.d/80-persistent-net.rules
Configure the udev rules:
Write the MAC addresses and names of NICs except eth0 and eth1 obtained in step 2 (those not contained in the /etc/udev/rules.d/70-persistent-net.rules file) to the /etc/udev/rules.d/80-persistent-net.rules file so that the names and sequence of NICs do not change after the BMS is restarted.

Ensure that the NIC MAC address and name are lowercase letters.

vim /etc/udev/rules.d/80-persistent-net.rules

The modification result is as follows:

After the modification, press Esc, enter :wq, save the configuration, and exit.
Run the following commands to copy the network configuration file /etc/sysconfig/network-scripts/ifcfg-bond0 to generate the /etc/sysconfig/network-scripts/ifcfg-bond1 file, and copy the /etc/sysconfig/network-scripts/ifcfg-eth0 file to generate the /etc/sysconfig/network-scripts/ifcfg-eth3 and /etc/sysconfig/network/ ifcfg-eth5 files:
cp -p /etc/sysconfig/network-scripts/ifcfg-bond0 /etc/sysconfig/network-scripts/ifcfg-bond1

cp -p /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth3

cp -p /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth5
Run the following commands to edit the /etc/sysconfig/network-scripts/ifcfg-eth3 and /etc/sysconfig/network-scripts/ifcfg-eth5 files:
- vim /etc/sysconfig/network-scripts/ifcfg-eth3
  Edit the eth3 network configuration file as follows:
```
USERCTL=no
MTU=8888
NM_CONTROLLED=no
BOOTPROTO=static
DEVICE=eth3
TYPE=Ethernet
ONBOOT=yes
MASTER=bond1
SLAVE=yes
```
  Change the value of BOOTPROTO to static, that of DEVICE to the network device name eth3, and that of MASTER to the port name of the user-defined VLAN (bond1). Retain values of other parameters.
- vim /etc/sysconfig/network-scripts/ifcfg-eth5
  Edit the eth5 network configuration file as follows (similar to eth3):
```
USERCTL=no
MTU=8888
NM_CONTROLLED=no
BOOTPROTO=static
DEVICE=eth5
TYPE=Ethernet
ONBOOT=yes
MASTER=bond1
SLAVE=yes
```
Run the following command to edit the /etc/sysconfig/network-scripts/ifcfg-bond1 file:
vim /etc/sysconfig/network-scripts/ifcfg-bond1

Edit the file as follows:
```
MACADDR=f4:4c:7f:3f:da:07
BONDING_MASTER=yes
USERCTL=no
ONBOOT=yes
NM_CONTROLLED=no
BOOTPROTO=static
BONDING_OPTS="mode=1 miimon=100"
DEVICE=bond1
TYPE=Bond
IPADDR=10.10.10.3
NETMASK=255.255.255.0
MTU=8888
```
Where,
- Change the value of MACADDR to the MAC address of eth3 or eth5.
- Change the value of BOOTPROTO to static.
- Change the value of DEVICE to bond1.
- Change the value of IPADDR to the IP address to be allocated to bond1. If the IP address planned for the user-defined VLAN does not conflict with the VPC network segment, you can plan the IP address as needed, only to ensure that BMSs communicating through the user-defined VLAN are in the same network segment as the user-defined VLAN. An example value is 10.10.10.3.
- Set the value of NETMASK to the subnet mask of the IP address configured for bond1.
Retain values of other parameters.

After the modification, press Esc, enter :wq, save the configuration, and exit.
Run the following command to enable port group bond1 of the user-defined VLAN:
ifup bond1
```
Determining if ip address 10.10.10.3 is already in use for device bond1...
```
Perform the preceding operations to configure other BMSs.
After all BMSs are configured, ping the IP addresses of other BMSs from each BMS.

Configuring a User-defined VLAN (Red Hat, CentOS, Oracle Linux, and EulerOS)